Residues of antibiotics and other toxins in foods are a major food safety concern. Food is tested worldwide for antibiotics, mycotoxins and other contaminants. One type of test method uses what is commonly known as a lateral flow test strip.
Lateral-flow test strips for detecting one or more analytes in a fluid sample may include a capture agent immobilized within a region of the test sometimes referred to as a detection zone. Detection zones can include test zones and control zones. A typical capture agent has binding affinity for a substance that may be in a mobile phase of the test strip.
Lateral-flow tests in which the binding of a substance from a mobile phase to a capture agent generates a visible signal, that can be interpreted visually or using a reader, such as a spectrophotometer, are well known in the art. Examples of such tests are described in U.S. Pat. No. 5,985,675, issued Nov. 16, 1999; and U.S. Pat. No. 6,319,466, issued Nov. 20, 2001, and U.S. patent application Ser. No. 10/289,089, filed Nov. 6, 2002 (based on U.S. Provisional Application 60/332,877, filed Nov. 6, 2001), and U.S. Pat. No. 7,410,808, issued Aug. 12, 2008, all of which are incorporated herein by reference. Many such tests utilize a signal component, such as a colored particle, to generate the visible signal. Other such tests utilize a reaction, such as an enzyme-substrate reaction, to generate the visible signal. Generally, tests require a binding substance to be linked to the signal component. If the binding of the binding substance to the signal component is weak or inconsistent, an additional linkage may be necessary.